*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: "PingFang SC","Microsoft YaHei UI",sans-serif;
}
nav{
    position: fixed;
    top: 0;
    left: 0;
    right: 0;

    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 5vm;
    height: 80px;
    background-color: black;
    box-shadow: 0 0 20px black;
}
.logo{
    flex: 1;
    margin-left: 40px;
}
.nav-menu{
    flex: 1;
    display: flex;
    justify-content: space-between;

    max-width: 550px;
    margin-right: 40px;
}

.nav-menu li{
    list-style: none;
    font-weight: 600;
}
.nav-menu .active,.nav-menu li:hover{
    text-shadow: 0 3px 6px white;
}
.nav-menu li a{
    text-decoration: none;
    color: white;
}
.burger div{
    width: 25px;
    height: 3px;
    background-color: white;
    margin: 4px;
}
.burger{
    display: none;
}
@media screen and (max-width:640px){
    .nav-menu{
        position: absolute;
        top: 80px;
        right: 0;
        bottom: 0;
        width: 50vw;
        height: calc( 100vh - 80px);
        margin-right: 0;

        background-color: black;
        flex-direction: column;
        align-items: center;
        justify-content: flex-start;

        transform: translateX(100%);
        transition: 0.4s ease-in-out;
    }

    .nav-menu.open{
        transform: translateX(0);
        box-shadow: 0 0 20px black;
    }
    .nav-menu li{
        margin: 3vh;
        transform: translateX(20px);
        opacity: 0;
    }

    .burger{
        display: block;
        margin-right: 40px;
    }

    .burger.active div{
        transition: 0.3s ease-in-out 0.3s;
    }
    .burger.active .top-line{
        transform: rotate(45deg) translate(4px,6px);
    }
    .burger.active .middle-line{
        opacity: 0;
        transform: translateX(10px);
        transition: 0.3s ease-in-out;
    }
    .burger.active .bottom-line{
        transform: rotate(-45deg) translate(4px,-6px);
    }
    @keyframes slideIn {
        from{
            transform: translateX(20px);
            opacity: 0;
        }
        to{
            transform: translateX(0);
            opacity: 1;
        }
    }
}